This invention relates to arrangements for detecting gases and in particular for measuring carbon dioxide levels in breathing gas mixtures. The invention also relates to breathing apparatus, e.g. for underwater use.
It is desirable to monitor the composition of breathing gas mixtures to ensure that the concentration of carbon dioxide in the mixture remains below a predetermined maximum. This is particularly important in gas mixtures that are supplied to divers or other persons working under hostile conditions where the drowsiness induced by excessive carbon dioxide in the gas mixture could prove extremely dangerous.
A number of devices for detecting and measuring gases such as carbon dioxide are available. However, some of these devices are relatively expensive and none is sufficiently portable for monitoring in a breathing apparatus to provide remote sensing.